Machine human interaction has been a subject of continuous interest for researchers. Especially in the context of a computing device, manufacturers are competing with each other to introduce novel ways of human machine engagement for their customers. Gone are the days when a user had to remember programming language like commands to interact with a computer system. Graphic user interfaces (GUIs) and development of peripheral devices, such as, a mouse or a joystick, has changed the way a user interacts with a machine. In fact, modern day computer interaction has gone a few steps further ahead. Touch and gesture interfaces are the new paradigms of machine human interaction that adorns latest computing devices, including mobile systems.
Considering the variety of interactive options available, multimodal interaction is fast becoming a new norm for engagement with a machine. A user may employ a combination of interactive modes, such as, a touch interface and a keyboard, to communicate with a device. Speech may also be used along with other modes, such as, a mouse or a touchpad to provide a command. However, there may be situations where a speech interface may not be appropriate. For example, if a user is working in a noise free area, such as, a library or a hospital, it may not be desirable to employ a speech interface to interact with a computing device.